The Study And Design Of The Hand-held GPS Equipment

GPS(Global Positioning System) was initiated and has been carried out in the United States of America. It was designed originally for the purpose of military service. Later with its development, GPS had also showed great potential in civil applications. In fact, due to its excellent positioning strategies—round the clock and over the earth service as well as its high accuracy, GPS has already been successfully and widely applied in such fields as navigation, aerospace, survey, monitoring and dispatchment of mobile vehicles.GPS was built and maintained by America, which can serve civil use and military affairs .Because the process of satellitic orientation measure is affected by many exterior facts, GPS orientation has definite errors. Precision of generic civil signal is approximate 5 to 100m while military 10m.Certainly, with the improvement of measure techniques and methods, range of errors will shrink.The hand-held GPS receiver will exit the biggest potential in the global position system with its compact size ,low cost and all kinds of function.This thesis mostly researches and designs on the hand-held receiver of GPS and how to reduce the GPS fixed position error ,and discussing the hand-held receiver of GPS in many ways.The thesis designed and drew the GPS hardware electric circuit and introduced some main parts of the electric circuit detailedly such as the GPS receive module, microprocessor, memorizer, LCD display module and function key, etc. which was on the basis of detailed analysis and introduction of the the GPS fixed position principle. The thesis explained the GPS system software concretely, the format and reading method of GPS deferent data ,designed the flow chart of GPS software, researched and designed the functional picture,the operational method of scanning keyboard and the initialization function software of GPS orientation and navigation in detail. After repetitious investigations and examinations ,the thesis brought forward some effective methods of reducing errors,for exemple, the filter arithmetic of average value that can get rid of the radom disturbing signal fluctuating around one number and adaptable arithmetic that can get rid of the uncertain error disturbbing signal.The emphases of the thesis mostly focus on the decreasing method of the GPS fixed position error. The design and realization of the system puts forward some available methods aimed at how to decrease the GPS fixed position error and this is a difficult problem. Really, passing the test and imitate, these methods obtained to compare the good result, and the design of system obtains a preferable fruit and achieves expectant aim.